Sometimes, when retrieving a document, a user needs to retrieve documents of another field that match the document. At present, there are mainly two manners of matching cross-field documents. A first manner is performing matching between documents of different fields according to a similarity between text character strings of sentences in the documents of different fields, and a second manner is counting a similarity between vocabularies in documents of different fields, and performing matching between the documents of different fields according to a similarity of words in the documents of different fields.
In the first manner, sentences describing a same thing in different documents are not necessarily the same, and sentences describing a same thing in documents of different fields are far more different. Therefore, matching between cross-field documents according to a similarity between character strings cannot be performed accurately. In the second manner, matching between documents of different fields is performed according to a counted similarity between vocabularies in the documents of different fields, but words used to describe a same thing in the documents of different fields are quite different. Therefore, documents cannot be accurately matched merely according to the similarity between the vocabularies.